The iPhone 4 originally came with standard (if rather small) Phillips-head screws – making it relatively easy for customers to open up their own phones to perform basic DIY repairs.

But more recent versions – and phones that have been returned to Apple for repairs – have instead featured five-pointed ‘pentalobe’ screws, for which there are no widely-available screwdrivers that can unscrew them.

Gadget fans are speculating that this is a deliberate move by Apple to stop customers getting access to their own phone, to ensure that only Apple technicians can carry out repairs.

Gadget DIY site iFixit says : ‘there isn’t a single reputable supplier that sells exactly the same screwdrivers Apple’s technicians use—which is Apple’s point. They picked an obscure head that no one would have.’

It’s not the first time that Apple have rolled out the pentalobe screws to defeat customers wanting to get into their devices – larger versions of the screw also appeared on the MacBook Pro in 2009, stopping owners from replacing the battery. The new screws first started appearing on Japanese iPhone 4s last year – and now they have started cropping up on iPhones in the US and the UK.

That includes phones that have been brought into Apple for repair – iFixit reports that the phones will come back with the screws swapped out.

iPhone owners faced with the awkward screws do have a couple of options – iFixit is offering an ‘iPhone 4 Liberation Kit’ that includes screwdrivers that, while not a perfect fit for the pentalobe, will manage to unscrew them with a bit of effort. And Gizmodo think they’ve tracked down a wholesaler that offers a screwdriver that will fit – although they don’t guarantee that it will work.